Dynamo-electric machinery



Jan. 8-, 1924. 1,480,415

(I- A. PARSONS ET AL I DYNAMO ELECTRIC MACHINERY Filed April 50. 1923 2 Sheets-Sheet 1 Jan. 8 1924.

C. A. PARSONS ET AL DYNA MO ELECTRIC MACHINERY Fil d p il 30. 1923 2 Sheets-Sheet 2 Patented Jan. 8, 1924.

UNITED STATES 1,480,412 PATENT OFFICE.

CHARLES ALGERN'ON PARSONS AND JESSEL ROSEN, OF NEWCASTLE-ON-TYNE, ENG- LAND; SAID ROSEN ASSIGNOR T0 SAID PARSONS.

DYNAMIC-ELECTRIC MACHINERY.

Application filed April 30, 1923. Serial No. 635,663.

To all whom it may concern:

Be it known that we, CHARLES ALGERNON PARSONS, a subject of the King of Great Britain and Ireland, and JESSEL RosEN, a subject of the King of Great Britain and Ireland, and both residing at Heaton Works, Newcastle-on-Tyne, in the county of Northumberland, England, have invented certain new and useful Improvements in and Relating to Dynamo-Electric Machinery, of which the following is a specification.

This invention relates to improvements in dynamo-electric machines and more particularly to dynamo-electric machines with rotating fields. In this type, the exciting windings or coils are usually wound into insulated slots in the rotor body and are supported, with the interposition in some cases of protective shields, by metal keys driven into the slots near the rotor periphery, the coils, where they project at each end of the rotor, being supported by a metal cap, from which they are insulated.

With present designs, as is well known, the exciting windings, which are the seat of the generation of heat, reach a very much higher temperature than that of the surrounding metal owing to the low heat conductivity of the insulating material in the slot. When the machine is on load, the winding coils expand and lengthen in relation to the cooler surrounding metal, the movement being greatest at the ends of the winding under the supporting caps. This movement is more apparent on turbo-alternators, owing to the comparatively long length of rotor body employed, and is accentuated by the fact that the coefiicient of expansion of copper, of which material the winding consists, is higher than that of the surrounding metal, steel or iron. Since the rotor revolves at a high peripheral speed, the mechanical pressure due to centrifugal force between the caps and the coils is high with the result that the intervening insu lating materials, which have poor mechanical properties, are incapable of withstanding the abrasive action set up by the movement of the windings.

The object of the present invention is to overcome these difficulties.

With this object The invention consists in mechanicall attaching to those parts of the rotor wind ings projecting from the rotor body an insulated metal shield in rubbing contact with the supporting cap.

The invention also consists in shield indicated in the preceding paragraph which serves not only to take the friction of the supporting cap but, in addition, to hold in place the packing pieces between the projectingend coils.

The invention further consists in a shield as in the preceding paragraphs stamped out of sheet metal and bent to form clips for the purposes indicated.

The invention finally consists in the protective shields hereinafter described or indicated.

Referring to the accompanying drawings, which illustrate specific forms of the invention by way of example Figure 1 is a part longitudinal section through the rotatin magnet system of a dynamo-electric machine, showing the coil ends projecting beyond the rotor body;

Figure 2 is an expanded view of a part of the rotor end winding shown in Figure l Figure 3 is a part sectional view of an end coil showing the slipper in position, b

Figure 4 being a cross-sectional view taken on the line 4-4 of Figure 1, while finally Figure 5 shows a plan of the metal stamping from which the slipper according to one modification may be formed, and

Figure 6 a perspective view of the slipper after bending the stamping to shape.

Where desirable, the same reference symbols are used in the different figures to denote correspondin parts.

Certain known eatures of construction referred to in the preamble of this specification are indicated in the above drawings as follows :-The exciting windings or coils, a, (see Figure 4) are shown wound into insulated slots, I), and held in place by metal keys, 0, the projecting coils ends, d, being held against the action of centrifugal force by the end caps, e.

In carrying the invention into effect according to its simplest form, in conjunction with such a known structure, the protective shields take the form of trough-shaped slippers, f, of a suitable metal conforming to the profile of the coils, d, where they project from the rotor and are so arranged that the sides of the trough firmly grip the coils with which they are associated (see Figure 1). The ends, h, of the slippers pass under the metal wedges or keys, 0, fitted in the rotor slots, 6, near the periphery for supporting the coils against centrifugal force. The coils, a, d, are insulated from the supporting cap 6, and keys, 0, by mica, presspahn, 2', 2', (see Figures 1 and 4C) or similar insulation, and in the case of the projecting portions, this insulation may very conveniently take the form of slippers, 70, (see Figure nested respectively within. the protective shields, f, the supporting cap, 6, being placed in position after all the slippers have been assembled. r

Preferably each slipper, 7, is so formed that in addition to merely protecting the insulation from the friction of the supporting cap, 6, it also serves to hold in place the packing pieces, m, between the coils where they project from the rotor.

With this object, the slippers may be very conveniently made from stamped sheet metal, as shown in Figure 5, a lateral extension, n, being arranged as required on each side of the slipper in the neighbourhood of the packing pieces, m. After cutting the stamping along the dotted lines shown in Figure 5, each such extension is turned down at right angles into a slot provided in the corresponding packing piece, while the e-ndsof the turned down portion are also bent at right angles to form ears, 0, enclosing the packing piece between them, and thus securing it in position (see Figure 1)) In this way the use of tape or other binding material is avoided. The remainder of the stamping is turned down along its longitudinal edges to form a trough section.

One slipper may be fitted over two or more coils, if desired, this modification being especially convenient where the coils are banked together.

It will be seen that by the provision of a protective metal cover, mechanically attached to the end windings but electrically insulated therefrom, all movement takes place between the cover and cap, i. e., be tween metal and metal and not between metal and insulation as heretofore.

In addition the protecting shields or covers serve to protect the insulation on the coils when fitting or removing the caps.

While certain forms of the invention have been described in detail in order to make its nature clear, it is obvious that the structural details of the shield or shields may take other forms without departing from the principles involved.

Having now described our invention, what We claim as new and desire to secure by Letters Patent is 1. In dynamo-electric machinery, a rotor, coils held in slots in said rotor, and an individual shield covering the end of each coil, trough shaped in cross section.

2; In dynamo-electric machinery, a rotor, coils held in slots in said rotor, individual shields covering the end of each coil, trough-shaped in cross section, and similarly shaped insulation members be tween the coils and the shields.

3. In dynamo-electric machinery, a rotor, coils held in slots in said rotor, and a shield covering one end of each coil, the end of said shield gripping its coil.

4. In dynamo-electric machinery, a rotor, coils held in slots in said rotor, individual shields covering the end of each coil, and packing pieces between coils, said shields engaging said packing pieces.

5. In dynamoelectric machinery, a rotor, coils held in slots in said rotor, individual shields coveringthe end of each coil, packing pieces between coils having cut away portions in their ends, the shields having an end seated in the cut away portion of the packing pieces.

In testimony whereof we have signed our names to this specification.

CHARLES ALGERNON PARSONS. JESSEL ROSEN. 

